The theory and practice of prevention, forecast and warning on cyanobacteria bloom in Lake Taihu

综述了蓝藻水华预防、预测预警的重要意义及其理论与技术体系.基于作者所提出的将蓝藻水华形成分为休眠、复苏、生长和上浮聚集形成水华的四阶段理论,以及太湖蓝藻越冬、春季复苏和水华形成的时空规律,提出了太湖蓝藻水华的预防理念.综述了国内外蓝藻水华形成与预测研究进展,阐述了蓝藻水华形成关键过程的主导生态因子及其阈值:确定了水华蓝藻越冬的空间分布与生命特征,利用室内模拟实验和野外原位观测与捕捉,得到了蓝藻春季复苏的室内和野外温度阈值分别为14℃和9℃,发现了蓝藻复苏量与有效生理积温呈正相关的基本规律;初步揭示了水华蓝藻生长竞争优势形成的生物学与生态学机理以及光利用策略,利用细胞分裂频率法测定了夏季太湖水华蓝藻的原位生长速率为0.2-0.4;确定了在不同水文气象条件下,水华蓝藻在水体中垂直分布和在不同湖区之间输移的基本格局,发现藻类在水体中各层间百分含量的变异系数随着风浪的增大而减小,进一步证明了蓝藻水华形成是在适当水文气象要素驱动下,已经成为优势种群的水华蓝藻在湖体中空间位置的改变而引起的.建立了太湖蓝藻水华预测模型和工作流程,在2007年和2008年在太湖实施了未来3d的蓝藻水华预测预警,预测分析了2008年全年太湖蓝藻水华情势.对预测结果的回顾性评估与分析表明,目前已有的理论研究结果和预测工作流程可以对太湖蓝藻水华发生概率、发生地点和强度进行预测,预测准确率达到60%-80%.此外,还提出了未来蓝藻水华预测的研究方向.;The present article described the importance of prevention, forecast and warning of cyanobacteria bloom. The recent progresses of formation and forecast of cyanobacteria bloom were reviewed. Based on the theory of “four phases of cyanobacteria bloom development” and the temporal and spatial distribution of cyanobacteria overwintering, recruitment and bloom formation in Lake Taihu, the processes of cyanobacteria blooms and the dominant ecological factors during their development phases were studied. Field observations and laboratory simulating studies were performed to investigate horizontal distribution and life characteristics during the overwintering period. The threshold temperature for the recruitment of cyanobacteria was about 9 in the field resear ℃ ch. It was found that there was a positive relationship between effective accumulated temperatures and recruitment biomass of cyanobacteria. By the methods of frequency of dividing cells, the calculation of the growth rates in situ showed that the growth rates of Microcystis were from 0.2 to 0.4. The dynamics of vertical distribution of cyanobacteria in the transport process between different lake areas were investigated under different meteorological conditions, and the results supported the viewpoint that bloom formation is a shift in the vertical positioning of the cyanobacteria biomass which previously distributed through the water column, since the coefficients of variation of the vertical cyanobacteria distribution at different depths were negatively related to wind speeds. On the basis of the establishment of key factors and their thresholds of bloom formation, the bloom forecast model and flow chart ofcyanobacteria bloom forecast and warning were established. The bloom forecasts in 2007, 2008 and analysis of bloom trends of 2008 were implemented. The retrospective assessment of the forecast showed that it is possible to forecast the probability, location and extent of cyanobacteria bloom. The future research directions were also suggested.